Display device having a thin film glass layer

ABSTRACT

Provided is a display device. The display device includes a flexible display panel configured to display an image, and a window disposed on a display surface of the flexible display panel. The window includes a first protection layer, a thin film glass layer disposed on the first protection layer, and a second protective layer disposed on the thin film glass layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application is a Continuation of U.S.patent application Ser. No. 16/567,649, filed on Sep. 11, 2019, whichclaims priority under 35 U.S.C. § 119 to Korean Patent Application No.10-2018-0160268, filed on Dec. 12, 2018, the entire contents of whichare hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to a display device, and moreparticularly, to a display device having a thin film glass layer.

DISCUSSION OF THE RELATED ART

Electronic devices such as smart phones, tablet computers, notebookcomputers, and smart televisions are under development. These electronicdevices generally include a display module for displaying informationand imagery to a user. Electronic devices may further include variousother electronic modules in addition to the display module.

Recently, display devices have been developed to be capable of foldingor rolling without breaking. These flexible display devices incorporatea bending flexible display member. Unlike traditional flat panel displaydevices, flexible display devices may be folded or rolled, like paper.Flexible display devices may be easy to carry as they may be folded orrolled into a more convenient shape.

SUMMARY

The present disclosure provides a display device having increased inimpact resistance.

An embodiment of the present inventive concept provides a display deviceincluding a flexible display panel configured to display an image. Awindow is disposed on a display surface of the flexible display panel.The window includes a first protection layer, a thin film glass layerdisposed on the first protection layer, and a second protective layerdisposed on the thin film glass layer.

In an embodiment of the present inventive concept, the second protectionlayer may include a hard coating layer.

In an embodiment of the present inventive concept, the window mayfurther include a fingerprint prevention layer disposed on the secondprotection layer.

In an embodiment of the present inventive concept, the first protectionlayer may include a first shock absorption layer.

In an embodiment of the present inventive concept, the first protectivelayer may further include an internal adhesive layer adhering the firstshock absorption layer to the rear surface of the thin film glass.

In an embodiment of the present inventive concept, the secondprotection, layer may include a hard coating layer. A second shockabsorption layer is disposed between the hard coating layer and the thinfilm glass layer.

In an embodiment of the present inventive concept, the thin film glasslayer may have a thickness within a range of 30 μm to 70 μm.

In an embodiment of the present inventive concept, the flexible displaypanel may include an organic light emitting display panel including anorganic light emitting element.

In an embodiment of the present inventive concept, a display deviceincludes a display panel configured to display an image. The displaypanel includes a folding area that folds around a folding axis, and aplurality of non-folding areas that are adjacent to opposite sides ofthe folding area. A window is disposed on the display surface of thedisplay panel. The window includes a first protection layer, a thin filmglass layer disposed on the first protection layer, and a secondprotective layer disposed on the thin film glass layer.

In an embodiment of the present inventive concept, the display panel maybe folded out such that the display surface is exposed to the outside ormay be folded in so as to face the display surface.

In an embodiment of the present inventive concept, the second protectionlayer may include a hard coating layer.

In an embodiment of the present inventive concept, the hard coatinglayer may have a thickness within a range of 3 μm to 30 μm.

In an embodiment of the present inventive concept, the hard coatinglayer may include a urethane resin, an epoxy resin, an acrylic resin,and/or an acrylate resin.

In an embodiment of the present inventive concept, the hard coatinglayer may have an indentation hardness within a range of 15 to 40 HV.

In an embodiment of the present inventive concept, the window mayfurther include a fingerprint prevention layer disposed on the secondprotection layer.

In an embodiment of the present inventive concept, the first protectionlayer may include a first shock absorption layer.

In an embodiment of the present inventive concept, the first shockabsorption layer may have a thickness within a range of 10 μm to 60 μm.

In an embodiment of the present inventive concept, the first protectivelayer may further include an internal adhesive layer adhering the firstshock absorption layer to the rear surface of the thin film glass layer.

In an embodiment of the present inventive concept, the internal adhesivelayer may have a thickness within a range of 10 μm to 70 μm.

In an embodiment of the present inventive concept, the second protectionlayer may include a hard coating layer and a second shock absorptionlayer disposed between the thin film glass layer and the hard coatinglayer.

In an embodiment of the present inventive concept, the second shockabsorption layer may have a thickness within a range of 5 μm to 50 μm.

In an embodiment of the present inventive concept, the second shockabsorption layer may include a urethane resin, an epoxy resin, apolyimide resin, a polyamide resin, and/or an acrylate resin.

In an embodiment of the present inventive concept, the display panel mayinclude an organic light emitting display panel including an organiclight emitting element.

In an embodiment of the present inventive concept, a display deviceincludes a display panel configured to display an image. The displaypanel includes a folding area that folds around a folding axis, and aplurality of non-folding areas that are adjacent to opposite sides ofthe folding area. A window is disposed on the display surface of thedisplay panel. The window includes a thin film glass layer, a hardcoating layer disposed on the thin film glass layer, a shock absorptionlayer disposed on a rear surface of the thin film glass layer, and aninternal adhesive layer disposed between the thin film glass layer andthe shock absorption layer and adhering the shock absorption layer tothe rear surface of the thin film glass.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings are included to provide a furtherunderstanding of the present inventive concept, and are incorporated inand constitute a part of this specification. The drawings illustrateexemplary embodiments of the present inventive concept and together withthe description, serve to explain principles of the present inventiveconcept. In the drawings:

FIG. 1 is a perspective view illustrating a display device according toan embodiment of the present inventive concept;

FIG. 2 is a cross-sectional view taken along line I-I′ shown in FIG. 1 ;

FIGS. 3A to 3D are cross-sectional views illustrating the structure of awindow according to embodiments of the present inventive concept;

FIG. 4 is a perspective view of a foldable display device according toan embodiment of the present inventive concept;

FIG. 5A is a perspective view illustrating a state in which the displaydevice shown in FIG. 4 is folded in along a first folding axis;

FIG. 5B is a perspective view illustrating a state in which the displaydevice shown in FIG. 4 is folded out along a first folding axis;

FIG. 6A is a perspective view illustrating a state in which the displaydevice shown in FIG. 4 is folded in along a second folding axis;

FIG. 6B is a perspective view illustrating a state in which the displaydevice shown in FIG. 4 is folded out along a second folding axis;

FIG. 7A is a cross-sectional view of the display device in the folded instate shown in FIG. 5A, which is taken along fine II-II′;

FIG. 7B is a cross-sectional view of the display device in the foldedout state shown in FIG. 5B, which is taken along line III-III′;

FIGS. 8A to 8D are cross-sectional views illustrating the structure of awindow according to embodiments of the present inventive concept;

FIG. 9A is a cross-sectional view illustrating a folded out state of thewindow shown in FIG. 8A;

FIG. 9B is a cross-sectional view illustrating a folded out state of thewindow shown in FIG. 8B;

FIGS. 10A to 10D are process diagrams illustrating a manufacturingprocess of the window shown in FIG. 8A;

FIGS. 11A to 11E are process diagrams illustrating a manufacturingprocess of the window shown in FIG. 8B;

FIG. 12 is an exploded perspective view illustrating a display moduleaccording to an embodiment of the present inventive concept;

FIG. 13 is an equivalent circuit diagram illustrating a pixel includedin a display panel according to an embodiment of the present inventiveconcept; and

FIG. 14 is a cross-sectional view illustrating a part of the area of adisplay module according to an embodiment of the present inventiveconcept.

DETAILED DESCRIPTION

In describing exemplary embodiments of the present disclosureillustrated in the drawings, specific terminology is employed for sakeof clarity. However, the present disclosure is not intended to belimited to the specific terminology so selected, and it is to beunderstood that each specific element includes all technical equivalentswhich operate in a similar manner.

In this specification, when it is mentioned that a component (or, anarea, a layer, a part, etc.) is referred to as being “on”, “connectedto” or “combined to” another component, this means that the componentmay be directly on, connected to, or combined to the other component orone or more other components may be disposed between the mentionedcomponents.

Like reference numerals may refer to like elements throughout thedisclosure and the drawings. Additionally, in the drawings, thethicknesses, proportions, and dimensions of components may beexaggerated for the purpose of providing an effective description.However, it is to be understood that the relative sizes, thicknesses,shapes, and placements of the components depicted in the drawings doesindeed represent at least one exemplary embodiment of the presentinvention, and so the features illustrated may be seen as describing theproperties of an exemplary embodiment of the present invention.

It will be understood that the terms “first” and “second” are usedherein to describe various components but these components should not belimited by these terms. The above terms are used only to distinguish onecomponent from another. For example, a first component may be referredto as a second component and vice versa without departing from the scopeof the present inventive concept. The singular expressions includeplural expressions unless the context clearly dictates otherwise.

In addition, terms such as “below”, “the lower side” “on”, and “theupper side” are used to describe a relationship of configurations shownin the drawing. The terms are described as a relative concept based on adirection shown in the drawing.

In various embodiments of the present inventive concept, the term“include,” “including,” or “comprising,” specifies a property, a region,a fixed number, a step, a process, an element and/or a component butdoes not exclude other properties, regions, fixed numbers, steps,processes, elements and/or components and thus there may be otherelements along with the recited elements. However, the phrase“consisting of” specifies that no other constituents but those recitedcontribute to the element being described.

Hereinafter, an embodiment of the present inventive concept will bedescribed with reference to the drawings.

FIG. 1 is a perspective view illustrating a display device according toan embodiment of the present inventive concept, and FIG. 2 is across-sectional view taken along line I-I′ shown in FIG.

Referring to FIG. 1 , a display area DA and a non-display area NDA maybe defined in a display device DD1.

The display area DA is disposed on plane defined by a first directionaxis DR1 and a second direction axis DR2, and an image IM is displayedin the display DA. A third direction axis DR3 indicates the normaldirection of the display area DA, for example, a thickness direction ofthe display device DD1. The front surface (or an upper surface) and therear surface (or a lower surface) of each member are divided by thethird direction axis DR3. However, the directions that the first tothird direction axes DR1, DR2, and DR3 indicate may be convened to otherdirections as a relative concept. Hereinafter, first to third directionsrefer to the same reference numerals of the respective directions thatthe first to third direction axes DR1, DR2, and DR3 indicate.

The display device DD1 may be used in medium-sized electronic devicessuch as personal computers, notebook computers, personal digitalterminals, car navigation units, game consoles, portable electronicdevices, and cameras in addition to large-sized electronic devices suchas televisions, computer monitors, or digital billboards. In addition,other products may utilize the described display device DDI, and theproduces listed herein are offered as examples.

The non-display area NDA is adjacent to the display area DA. The imageIM is displayed exclusively within the display area DA and not withinthe non-display area NDA. A bezel area of the display device DD1 may bedefined by the non-display area NDA.

The non-display area NDA may at least partially surround the displayarea DA. For example, the non-display area NDA may adjoin one or moresides of the display area DA.

Referring to FIGS. 1 and 2 , the display device DD1 may include adisplay panel DP and a window WM. The display panel DP may be a flexibledisplay panel. For example, the display panel DP is flexible and may bedeformed by bending, folding, rolling, or the like. It is noted that asused herein, the terms “flexible,” “deformable,” “bendable,” “foldable,”“rollable,” etc. are meant to indicate that the display panel DP may bemanipulated in the stated manner, to a noticeable degree, repeatedly,without cracking or otherwise breaking.

As an example of the present inventive concept, the display panel DP maybe an organic light emitting diode (OLED) display panel. The displaydevice DD1 may further include at least one functional layer provided onthe display panel DP and at least one protection layer protecting thedisplay panel DP. The functional layer may include an input detectionlayer sensing a user input TC (for example, a touch operation, etc.)and/or an antireflection layer preventing reflection of external light.The protection layer may be configured to absorb an impact applied fromthe outside so as to protect the display panel DP from the impact. Theprotection layer may be provided on the upper part and/or the lower partof the display panel DP.

The window WM may be provided on the display panel DP and may define adisplay surface IS of the display device DD1 where the image IM isdisplayed. The window WM may be optically transparent. Accordingly, theimage IM generated on the display panel DP may be recognized by the userthrough the window WM.

The window WM includes a base layer 13S and a bezel layer BZL disposedon the rear surface of the base layer BS. The area where the bezel layerBZL is disposed may be defined as the non-display area NDA shown in FIG.1 . According to exemplary embodiments of the present invention, thewindow WM has a flat shape in the display area DA, but the presentinventive concept is not limited thereto, and the shape of the window WMmay be modified. For example one or more edges of the window WM may becurved.

The base layer BS may include a thin film glass layer. The base layer BSmay have a multi-layer or single-layer structure. For example, the baselayer BS may include a thin film glass layer and one or more windowfunctional layers formed on the thin film glass layer.

The bezel layer BZL may be one of the window functional layers. Thebezel layer BZL may have a single layer or a multilayer structure. Thebezel layer having a multilayer structure may include a pattern layerand an achromatic layer that provide a predetermined pattern. Thepattern layer may provide a hairline pattern. The achromatic hoer mayinclude an organic mixture including a black pigment or dye. The layersmay be formed by vapor deposition, printing, coating, or the like.

Since the window WM is flexible, the shape of the window WM may bedeformed together when the shape of the display panel DP is deformed.

In the display device DD1, an optically transparent adhesive layer AMmay be provided between the display panel DP and the window WM. Theadhesive layer AM may be a pressure sensitive adhesive (PSA), an opticalclear adhesive (OCA), or an optical clear resin (OCR). However, thematerial of the adhesive layer AM is not limited thereto.

The window WM transmits an image from the display panel DP and protectsthe display panel OP from an external impact at the same time, therebypreventing the display panel OP from being broken or otherwisemalfunctioning due to an external impact. The external impact mightotherwise causes a defect in the display panel DP and may be, forexample, pressure, stress or the like.

The window WM may be configured to reduce bending deformation,compressive deformation, and/or tensile deformation of the display panelDP due to point impact and surface impact, thereby preventing defects ofthe display panel DP. FIGS. 7A to 7D are cross-sectional viewsillustrating the structure of a window according to embodiments of thepresent inventive concept.

Referring to FIG. 3A, a window WM1, according to an embodiment of thepresent inventive concept, includes a first protection layer LPF1, athin film glass layer TG provided on the first protection layer LPF1,and a second protection layer UPF1 disposed on the thin film glass layerTG. The first and second protection layers LPF1 and UPF1 may be includedamong the window functional layers.

The thin film glass layer TG may be provided in a plate form. The thinfilm glass layer TG may be made of a glass material containing silicate.In an embodiment of the present inventive concept, the glass materialmay further include various materials so as to have excellentdurability, surface smoothness, and transparency. For example, the thinfilm glass layer TG may include a material such as aluminosilicate,borosilicate, boroaluminosilicate, and the like. In an embodiment of thepresent inventive concept, the thin film glass layer TG may furtherinclude an alkali metal, an alkaline earth metal, an oxide thereof, orthe like.

In an embodiment of the present inventive concept, the material of thethin film glass layer TG is not limited to the above-mentioned contents,and may be changed into various other glass materials.

The thin film glass layer TG may have a thickness within a range of 30μm to 70 μm. As used therein, all thickness ranges are understood to beinclusive. The thickness range of the thin film glass layer TG may bethin enough so that the window WM1 is flexible and does not crack orbreak, but rather bends freely. Further, when the window WM1 is appliedto curved, folding, bending and rolling display devices with a deformedshape (a shape that is other than planar), the thickness range of thethin film glass layer TG may be set to a thickness range in which therestorative force is not increased in each shape deformation.

The thin film glass layer TG may have a Young's modulus within a rangeof 40 GPa to 100 GPa. When the window WM1 is applied to curved, folding,bending and rolling display devices with a deformed shape, the modulusvalue range of the thin film glass layer TG may be set to a rangesuitable for each shape deformation.

The second protection layer UPF1 includes a hard coating layer HCdisposed on the upper surface of the thin film glass layer TG, The hardcoating layer HC is provided on the upper surface of the thin film glasslayer TG, for example, on the surface facing the user.

The hard coating, layer HC protects the thin film glass layer TG fromexternal impact. The hard coating layer HC may have higher strength thanthat of the thin film glass layer TG. As an example of the presentinventive concept, the hard coating layer HC may have an indentationhardness within a range of 15 HV to 40 HV. Therefore, the hard coatinglayer HC may prevent the phenomenon that the shape deformation occurs,for example, the phenomenon that micro-cracks, stamping, pressing, andthe like occur in the thin film glass layer TG due to point impact orsurface impact provided from the outside. As the indentation hardness ofthe hard coating layer HC increases, when the window WM1 is applied tocurved, folding, bending and rolling display devices which are deformedin shape, it is possible to cause window breakage.

The hard coating layer HC may include a urethane resin, an epoxy resin,an acrylic resin, and/or acrylate resin. The hard coating layer HC maybe formed on the thin film glass layer TG by a coating method. Forexample, the hard coating layer HC may be formed on the thin film glasslayer TG using a method such as slot die coating, spin coating, and/orthe like.

The hard coating layer HC may have a thickness within a range of 3 μm to30 μm. The thickness range of the hard coating layer HC may be set sothat the window WM1 is flexible. Further, when the window WM1 is appliedto curved, folding, bending, and rolling display devices with a deformedshape, the thickness range of the hard coating layer HC may be set to athickness range in which the restorative force is not increased in eachshape deformation.

The first protection layer LPF1 includes a first shock absorption layerLCF1 disposed on a rear surface of the thin film glass layer TG and aninternal adhesive layer IAM bonding the first shock absorption layerLCF1 to the rear surface of the thin filth glass layer TG.

The first shock absorption layer LCF1 is provided on the rear surface ofthe thin film glass layer TG, for example, on the surface not facing theuser. The first shock absorption layer LCF1 may be a layer enhancing theimpact resistance of the window WMI and preventing the window WM1 fromshattering when it is broken (e.g. provides shatter resistance).

The first shock absorption layer LCF1 includes urethane resin, epoxyresin, polyester resin, polyether resin, acrylate resin,acrylonitrile-butadiene-styrene (ABS) resin, and/or rubber (e.g. naturalor synthetic). As an example of the present inventive concept, the shockabsorption layer LCF1I may include phenylene, polyethylene terephthalate(PET), polyimide (PI), polyamide (PAI), polyethylene naphthalate (PEN),and/or polycarbonate (PC).

The first shock absorption layer LCF1 may be attached to the rearsurface of the thin film glass layer TG by the internal adhesive layerJAM The internal adhesive layer (IAM) may be a pressure sensitiveadhesive (PSA), an optical clear adhesive (OCA), and/or an optical clearresin (OCR).

In one embodiment of the present inventive concept, each of the firstshock absorption layer LCF1 and the internal adhesive layer IAM may havea thickness within a tango of 10 μm to 70 μm. In one embodiment of thepresent inventive concept, the first shock absorption layer LCF1 mayhave a Young's modulus within a range of 1 GPa to 7 Gpa, and theinternal adhesive layer IAM may have a Young's modulus greater than 0Mpa and less than 1 Mpa.

Although it is shown in FIG. 3A that the first shock absorption layerLCF1 is coupled to the thin film glass layer TG by the internal adhesivelayer IAM, the present inventive concept is not limited thereto. Forexample, the first shock absorption layer LCF1 may be formed directly onthe rear surface of the thin film glass layer TG.

The window WM1 may further include a fingerprint prevention layer AFdisposed on the second protection layer UPF1. The fingerprint preventionlayer AF may be a contamination prevention layer that preventscontamination, such as a user's handprint e.g., fingerprints).

For example, the fingerprint prevention layer AF may be an oleophobiccoating that may reduce the propensity of hand oils, such as those thatmay be given off by a user's finger, from adhering to the window WM1and/or may make it easier for the window to be cleaned of anyfingerprints that may stick thereto.

The window WM1 may further include an antireflection layer preventingexternal light from being reflected from the upper surface of the thinfilm glass layer TG. The antireflection layer may be provided on thesecond protection layer UPF1 or between the second protection layer UPF1and the thin film glass layer TG.

The bezel layer BZL is provided corresponding to the non-display areaNDA shown in FIG. 1 . In an embodiment of the present inventive concept,the bezel layer BZL, may be disposed on the rear surface of the firstprotection layer LPF1. For example, the bezel layer BZL may be formed onthe rear surface of the first shock absorption layer LCF1. The bezellayer BZL may include an organic layer and/or an inorganic layer havinga predetermined color. The bezel layer BZL may include a dye or apigment so as to be a predetermined color. For example, the bezel layerBZL may include a black dye or pigment so as to appear black and blendin with the display area DA when it is inactive (e.g. not displaying animage).

In an example of the present inventive concept, the bezel layer BZL maybe omitted and may be disposed on another layer.

Referring to FIG. 3B, in the window WM2, according to an embodiment ofthe present inventive concept, the second protection layer UPF2 mayfurther include a second shock absorption layer UCF disposed between thethin film glass layer TG and the hard coating layer HC.

The second shock absorption layer UCF is provided on the upper surfaceof the thin film glass layer TG, for example, on the surface facing theuser. The second shock absorption layer UCF may be a layer increasingthe impact resistance of the window WM2.

The second shock absorption layer UCF may be formed on the upper surfaceof the thin film glass layer TG by a coating method. For example, thesecond shock absorption layer UCF may be formed on the upper surface ofa thin film glass layer TG using a dip coating, a slot die coating, aspin coating, or the like.

The second shock absorption layer. UCF may include a methane resin, anepoxy resin, a polyimide (PI) resin, a polyamide resin, and/or anacrylate resin, which may be formed on a thin film glass layer TGthrough a coating method. In an embodiment of the present inventiveconcept, the second shock absorption layer UCF may include polyimideand/or polyamide.

The second shock absorption layer UCF may have a thickness within arange of 5 μm to 50 μm. In an embodiment of the present inventiveconcept, the second shock absorption layer UCF may have a thicknesswithin a range of 10 μm. Also, the second shock absorption layer LAT mayhave a Young's modulus within a range of 1 Gpa to 7 Gpa.

Although a structure where the second shock absorption layer UCF isformed directly on the upper surface of the thin film glass layer TG isshown in FIG. 3B, the present inventive concept is not limited thereto.For example, the second shock absorption layer UCF may be coupled to theupper surface of the thin film glass layer TG through the adhesivelayer. In such a way, when the second shock absorption layer UCF isattached to the thin film glass layer TG through the adhesive layer, thesecond shock absorption layer UCF may include a polyimide resin, apolyamide resin, a polyester resin, a polyether resin, an acrylateresin, an acrylonitrile-butadiene-styrene (ABS) resin, and or rubber(e.g. natural or synthetic).

According to the window WM2, the first protection layer LPF1 includes afirst shock absorption layer LCF1 and an internal adhesive layer IAM.The structure of the first protection layer LPF1 shown in FIG. 3B is thesame as that of the first protection layer LPF1 shown in FIG. 3A, andthus a redundant description will be omitted. It is to be understoodthat herein, to the extent that redundant description is omitted, theelements that are not described may be at least similar to correspondingelements that are described elsewhere in the disclosure.

Referring to FIG. 3C, in the window WM3, according to an embodiment ofthe present inventive concept, since the second protection layer UPF1has the same structure as the second protection layer UPF1 shown in FIG.3A, and thus a redundant description will be omitted.

The window WM3 includes a third shock absorption layer LCF2. The thirdshock absorption layer LCF2 may be formed on the rear surface of thethin film glass layer TG through a coating method unlike the first shockabsorption layer LCF1 shown in FIGS. 3A and 3B. For example, the thirdshock absorption layer LCF2 may be directly formed on the rear surfaceof the thin film glass layer TG using a dip coating, a slot die coating,a spin coating, or the like.

The third shock absorption layer LCF2 may include a urethane resin, anepoxy resin, a polyimide resin, a polyamide resin, and/or an acrylateresin. In an embodiment of the present inventive concept, the firstshock absorption layer LCF2 may include polyimide (PI) and/or polyamide(PAI).

The third shock absorption layer LCF2 may have a thickness within arange of 5 μm to 70 μm. In an embodiment of the present inventiveconcept, the third shock absorption layer LCF2 may have a thicknesswithin a range of 50 μm. Also, the third shock absorption layer LCF2 mayhave a Young's modulus within a range of 1 Gpa to 7 Gpa. The thicknessof the third shock absorption layer LCF2 may have one of the abovethickness ranges so that window WM3 has the desired impact resistance.

Referring to FIG. 3D, in the window WM4, according to an embodiment ofthe present inventive concept, since the second protection layer UPF2has the same structure as the second protection layer UPF2 shown in FIG.3B, and thus a redundant description will be omitted.

In addition, the window WM4, since the first protection layer LPF2 hasthe same structure as the first protection layer LPF2 shown in FIG. 4and thus a redundant description will be omitted.

However, the third shock absorption layer LCF2 of the first protectionlayer LPF2 and the second shock absorption layer LCF of the secondprotection layer UPF2 are both formed on the thin film glass layer TGthrough a coating method. The second shock absorption layer UCF and thethird shock absorption layer LCF2 may be formed on the upper surface andthe rear surface of the thin film glass layer TG, respectively, throughseparate coating processes.

However, in an example of the present inventive concept, the second andthird shock absorption layers UCF and LCT2 may be simultaneously coatedon the thin film glass layer TG. For example, the second and third shockabsorption layers UCF and LCF2 may be simultaneously coated on the uppersurface and the rear surface of the thin film glass layer TG through adip coating method, respectively.

Each of the windows WM1 to WM4 described with reference to FIGS. 3A to3D may have a Young's modulus within a range of 30 GPa to 100 GPa.

FIG. 4 is a perspective view of a display device according to anembodiment of the present inventive concept. FIG. 5A is a view showing astate in which the display device shown in FIG. 4 is folded in along afirst folding axis, and FIG. 5B is a view showing a state in which thedisplay device shown in FIG. 4 is folded out along the first foldingaxis.

Referring to FIGS. 4 and 5A, the display device DD2 may be a foldabledisplay device. It may be folded based on a folding axis (e.g., thefirst folding axis FX1, and the second folding axis FX2) extending in apredetermined direction. Hereinafter, a folded state based on thefolding axes FX1 and FX2 is defined as a folding state, and an unfoldedstate is defined as the non-folding state.

A plurality of areas may be defined in the display device DD2 accordingto the operation mode. The plurality of areas may be divided into afolding area FA and at least one non-folding area NFA1 or NFA2. Thefolding area FA is defined between two non-folding areas NFA1 and NFA2.

In an exemplary embodiment of the present inventive concept, thenon-folding areas NFA1 and NFA2 may include a first non-folding areaNFA1 and a second non-folding area NFA2. The first non-folding area NFA1is adjacent to one side of the folding area FA in the first directionDR1, and the second non-folding area NFA2 is adjacent to the other sideof the folding area FA in the first direction DR1.

The display device DD2 may be folded in or folded out. Herein, folded inrefers to the display surface IS folded to face each other, and foldedout refers to the rear surface of the display device DD2 folded to faceeach other. Thus, in the folded in state, the display device DD2 isfolded such that the display surface IS is not exposed and is protected,although it is also not particularly visible in this state. In thefolded out state, however, the display device D12 is folded such thatthe display surface IS is fully exposed, and although it is notprotected in this state, the display surface IS remains visible.

The folding area FA is an area that forms a curvature substantiallycorresponding to a folding area based on the first or second foldingaxis FX1 or FX2. Here, the first folding axis FX1 may extend in thesecond direction DR2, e.g., the major axis direction of the displaydevice DD2, and the second folding axis FX2 may extend in the firstdirection DR1, e.g., the minor axis direction of the display device DD2.

The display device DD2 shown in FIG. 5A may be folded in such that thedisplay surface IS of the first non-folding area NFA1 faces the displaysurface IS of the second not folding area NFA2.

Referring to FIG. 5B, the display device DD2 may be folded out withrespect to the first folding axis FX1. When the display device DD2 isfolded out, the display surface IS may be exposed to the outside.

In the display device DD2, folding in and folding out may occur at thesame time. However, in an embodiment of the present inventive concept,the display device DD2 may be folded in or folded out.

It is noted that according to some exemplary embodiments of the presentinvention, some display devices may be configured to fold from anunfolded state to a folded in state, but not a folded out state, whileother display devices may be configured to fold from an unfolded stateto a folded out state, but not a folded in state. Display devices suchas these may thereby only fold into one or the other folding state.However, other display devices may be configured to fold into either thefolded in state or the folded out state.

It is also noted that while only one fold has been shown here, exemplaryembodiments of the present invention may be multiply folded such thattwo opposite ends each fold towards the center (e.g. non-overlappingfolds) or the display device may be folded in half lengthwise and thenfolded half again widthwise (e.g. overlapping folds) by applying thedisclosed structure and techniques multiple times.

FIG. 6A is a view showing a state in which the display device shown inFIG. 4 is folded in along a second folding axis, and FIG. 6B is a viewshowing a state in which the display device shown in FIG. 4 is foldedout along the second folding axis.

It is noted that here again, it may either be a single device that canbe folded along either folding axis or different devices may beconfigured to fold along different folding axes.

Referring to FIGS. 6A and 6B, the display device DD2 may be folded in orfolded out with respect to the second folding axis FX2. The secondfolding axis FX2 may extend along the first direction DR1 and may be inthe minor axis direction of the display device DD2.

The display device DD2 includes the first and second folding axes FX1and FX2 and is capable of folding in either the minor axis direction orthe major axis direction. However, in an example of the presentinventive concept, the display device DD2 may have only one foldingaxis, which may be either the first or second folding axes FX1 and FX2.

In the present embodiment, one folding area FA is defined in the displaydevice DD2, but the present inventive concept is not limited thereto.According to an embodiment of the present inventive concept, a pluralityof folding areas may be defined in the display device DD2. In thisrespect, the single device may be folded M one or more of a number ofdifferent ways.

FIG. 7A is a cross-sectional view of the display device in the folded instate shown in FIG. 5A, which is taken along line II-II′.

Referring to FIGS. 5A and 7A, the display device DD2 is folded in withrespect to the first folding axis FX1. The display device DD2 includes adisplay module DM and a window FWM. The display module DM includes aprotection layer PM, a display panel DP, a functional layer FC, a firstadhesive layer AM1, and a second adhesive layer AM2.

The display panel DP may be a flexible display panel. Accordingly, thedisplay device DD2 may be folded or unfolded around the first foldingaxis FX1. As an example of the present inventive concept, the displaypanel DP may be an organic light emitting diode (OLED) display panel.

As an example of the present inventive concept, the display panel DP mayfurther include an input detection unit for detecting an external input.The input detection unit may be integrated into the display panel DPthrough at least one continuous process. For example, the inputdetection unit may be disposed directly on the thin film encapsulationlayer of the display panel DP. Here, the direct placement means that theinput detection unit is disposed on the display panel DP without aseparate adhesive member interposed therebetween. The input detectionunit will be described later in detail with reference to FIG. 14 . In anembodiment, the input detection unit may be disposed on the displaypanel DP in the form of a panel.

The window FWM may include a flexible material and may be folded orunfolded around the first folding axis FX1. The window FWM will bedescribed later in detail with reference to FIGS. 8A to 9B.

At least one functional layer VC may be disposed between the displaypanel DP and the window FWM. As an example of the present inventiveconcept, the functional layer FC may be an antireflection layer blockingexternal light reflection. The antireflection layer may prevent theelements constituting the display panel DP from being visuallyrecognized front the outside by the external light incident through thefront surface of the display device DD2. The antireflective layer mayinclude a polarizing film and/or a phase retardation film. The number ofphase retardation films and the phase retardation length (λ/4 or λ/2) ofthe phase retardation film may be determined according to the operationprinciple of the antireflection layer.

In an embodiment of the present inventive concept, the functional layerFC may include a plurality of functional layers. In this case, eachfunctional layer may perform different functions.

The display panel DP and the functional layer FC may be adhered to eachother through the second adhesive layer AM2.

A protection layer PM may be disposed on the rear surface of the displaypanel DP. The protection layer PM may include a polymeric material. Theprotection layer PM may absorb an impact applied from the outside toprotect the display panel DP from impact. The protection layer PM may beadhered to the rear surface of the display panel DP through the firstadhesive layer AM1.

It is shown in FIG. 7A that the protection layer PM is located on therear surface of the display panel DP, but the present inventive concept,is not limited thereto. For example, a protection layer may beadditionally formed on the upper surface of the display panel DP, forexample, between the functional layer FC and the display panel DP, orthe upper surface of the functional layer FC, for example, between thefunctional layer FC and the window FWM.

The protection layer PM may include a polymeric material. In anembodiment of the present inventive concept, the protection layer PM mayinclude a plastic film as a base layer. The protection layer PM mayinclude a plastic film including polyethersulfone (PES), polyacrylate,polyetherimide (PEI), polyethylenenaphthalate (PEN),polyethyeneterephthalate (PET), polyphenylene sulfide (PPS),polyarylate, polyimide (PI), polycarbonate (PC), and/or poly(aryleneethersulfone).

A material constituting the protection layer PM is not limited toplastic resins and may include an organic/inorganic composite material.The protection layer PM may include an inorganic material filled in thepores of a porous organic layer and an organic layer. In an embodimentof the present inventive concept, the protection layer PM may be made ofa hydrophilic material. Therefore, the protection layer PM may preventexternal moisture from penetrating the display panel DP.

The window FWM may be fixed to the display module DM through the thirdadhesive layer AM3. For example, the window FWM may be fixed to theupper surface of the functional layer FC of the display module DM.

The first to third adhesive layers AM1 to AM3 may be opticallytransparent. The first to third adhesive layers AM1 to AM3 may be anadhesive layer hardened and manufactured after a liquid adhesivematerial is applied, or may be a separately manufactured adhesive sheet.For example, the first to third adhesive layers AM1 to AM3 may each be apressure sensitive adhesive (PSA), an optical clear adhesive (OCA),and/or an optical clear resin (OCR). In an embodiment of the presentinventive concept, at least one of the first to third adhesive layersAM1 to AM3 may be omitted.

According to FIG. 7A, the display device DD2 may be folded in withrespect to the first folding axis FX1 by the user's operation. Duringfolding in, the upper surface of the window FWM, for example, the uppersurface corresponding to the first non-folding area NFA1, may face theupper surface corresponding to the second non-folding area NFA2.

During folding in, the curvature radius r1 of the display device DD2 maybe defined as the separation distance from the first folding axis FX1 tothe upper surface of the window MM.

In the folding state, the first non-folding area NFA1 and the secondnon-folding area NFA2 may face each other. For example, the firstnon-folding area NFA1 and the second non-folding area NFA2 may face eachother and be parallel to each other. The area of the folding area FA isnot fixed but may be determined according to the curvature radius r1.The display device DD2 may receive or display an image in a foldedstate.

FIG. 7B is a cross-sectional view of the display device in the foldedout state shown in FIG. 5B, which is taken along line III-III′.

Referring to FIGS. 7B and 5B, the display device DD2 may be folded outwith respect to the first folding axis FX1 by the user's operation.During folding out, the upper surface of the window FWM may be exposedto the outside.

During folding out, the curvature radius r2 of the display device DD2may be defined as the separation distance from the first folding axisFX1 to the rear surface of the protection layer PM.

Referring to FIGS. 7A and 7B, the distance d1 (e.g., the first windowcurvature radius) between the first folding axis FX1 and the uppersurface of the window FWM during folding in is different from thedistance d2 (e.g., the second window curvature radius) between the firstfolding axis FX1 and the upper surface of the window FWM during foldingout.

During folding in, the curvature radius r1 of the display device DD2 maybe the same as the first window curvature radius d1. However, duringfolding out, the second window curvature radius r2 is larger than thecurvature radius r1 of the display device DD2. For example, the windowFWM employed in the folding in display device DD2 is located at theinnermost position with respect to the first folding axis FX1 of thedisplay device DD2, and receives a large bending stress. Therefore, thewindow FWM employed in the folding in display device DD2 requires a lowbendability limit. Here, the bendability limit may be a curvature radiuslimit. The curvature radius limit may be defined as the minimumcurvature radius that does not cause breaking, cracking, and/ordelamination of the window FWM during bending.

The window FWM employed in the folding out display device DD2 is locatedat the outermost position with respect to the first folding axis FX1 ofthe display device DD2, and the window FWM receives a less bendingstress. Thus, the window FWM employed in the folding out display deviceDD2 may require a higher bendability limit than the window FWM employedin the folding in display device DD2.

FIGS. 8A to 8D are cross-sectional views illustrating the structure of awindow according to embodiments of the present inventive concept. FIG.9A is a cross-sectional view illustrating a folding out state of thewindow shown in FIG. 8A. FIG. 9B is a cross-sectional view illustratinga folding out state of the window shown in FIG. 8B.

Referring to FIGS. 8A and 9A, a window FWM1, according to an embodimentof the present inventive concept, includes a first protection layer athin film glass layer TG provided on the first protection layer LPF1,and a second protection layer UPF1 disposed on the thin film glass layerTG.

The thin film glass layer TG may be provided in a plate form. The thinfilm glass layer TG may be made of a glass material containing silicate.

The thin film glass layer TG may have a thickness within a range of 30μm to 70 μm. The thickness range of the thin film glass layer TG may beset so that the window FWM1 is flexible. The thickness range of the thinfilm glass layer TG may be set to a thickness range in which therestorative force against the shape deformation during folding of thewindow FWM1 is not increased. As one example of the present inventiveconcept, the thin film glass layer TG may have a thickness within arange of 30 μm to 70 μm.

The second protection layer UPF1 includes a hard coating layer HCdisposed on the upper surface of the thin film glass layer TG. The hardcoating layer HC is provided on the upper surface of the thin film glasslayer TG, for example, on the surface facing the user. The hard coatinglayer HC protects the thin film glass layer TG from external impact.

The hard coating layer HC may have higher indentation hardness than thethin film glass layer TG. Therefore, the hard coating layer HC mayprevent the phenomenon that the shape deformation occurs, for example,the phenomenon that micro-cracks, stamping, pressing, and the like occurin the thin film glass layer TG due to point impact or surface impactprovided from the outside.

However, if the indentation hardness of the hard coating layer HCincreases, it may cause window breakage during folding of the windowFWM1. Accordingly, as an example of the present inventive concept, thehard coating layer HC may have an indentation hardness within a range of151 HV to 40 HV.

The thickness range of the hard coating layer HC may be set so that thewindow FWM1 is flexible. In addition, the hard coating layer HC may havea thickness range in which the restorative force on shape deformationdoes not increase when the window FWM1 is folded. As one example of thepresent inventive concept, the hard coating layer HC may have athickness within a range of 3 μm to 30 μm. Preferably, the hard coatinglayer HC may have a thickness within a range of 6 μm to 14 μm.

The first protection layer LPF1 includes a first shock absorption layerLCF1 disposed on a rear surface of the thin film glass layer TG and aninternal adhesive layer IAM for bonding the first shock absorption layerLCF1 to the rear surface of the thin film glass layer TG.

The first shock absorption layer LCF1 is provided, on the rear surfaceof the thin. film glass layer TG, for example, on the surface not facingthe user. The first shock absorption layer LCF1 may be a layer enhancingthe impact resistance of the window FWM1 and preventing the damage. Thefirst shock absorption layer LCF1 may be attached to the rear surface ofthe thin film glass layer TG by the internal adhesive layer IAM. In oneembodiment of the present inventive concept, each of the first shockabsorption layer LCF1 and the internal adhesive layer IAM may have athickness within a range of 10 μm to 70 μm.

The window FWM1 may further include a fingerprint prevention layer AFdisposed on the second protection layer UPF1. The fingerprint preventionlayer AF may be a contamination prevention layer that preventscontamination, such as a user's handprint e.g., fingerprints).

The bezel layer BZL is provided corresponding to the non-display areaNDA shown in FIG. 1 . In an embodiment of the present inventive concept,the bezel layer BZL may be disposed on the rear surface of the firstprotection layer LPF1.

In such a way, by additionally placing a hard coating layer HC on theupper surface of the thin film glass layer TG, the impact resistance ofthe window FWM1 may be increased.

Impact resistance may be checked by point impact test or surface impacttest. Point impact refers to the impact applied to a window when apointed object, such as a pen, falls from an arbitrary height from awindow surface to the window surface. Surface impact refers to theimpact that a device, such as a ball, applies on the window, and thesurface impact test measures the amount of impact load that the windowabsorbs when a ball of a predetermined size and weight falls to theupper part of the window. Under the same conditions, the point impactand surface impact tests were performed on the window FWM1 with the hardcoating layer HC and a comparison window with the hard coating layer HCremoved. It is shown that the window FWM1 shown in FIGS. 8A and 9Aabsorbs impacts up to 9 cm from the surface of the window FWM1 in thepoint impact test and the surface impact test, but the comparison windowabsorbs impacts up to 4 cm and 5 cm in the point impact test and thesurface impact test. For example, when the hard coating layer HC isprovided, impact resistance is increased.

As shown in FIG. 9A, in the window FWM1, a folding area FA and first andsecond non-folding areas NFA1 and NFA2 spaced apart from the foldingarea FA may be defined. The folding axis FX1 may be located within thefolding area FA and the window FWM1 may be folded out with respect tothe folding axis FX1. Here, the out-folding state of the window FWM1 maybe defined to be a folded state so that the upper surface of the windowFWM1, e.g., the fingerprint prevention layer AF, is exposed to theoutside.

The curvature radius R1 of the folded out window FWM1 may be defined asthe distance from the folding axis FX1 to the rear surface of the firstprotection layer LPF1. The curvature radius limit that the window FWM1may withstand without bending may be defined as bendability limit. Thebendability limit of the window FWM1, according to FIGS. 8A and 9A, maybe approximately 2.5 mm.

Referring to FIGS. 8B and 9B, in the window FWM2, according to anembodiment of the present inventive concept, a second protection layerUPF2 may further include a second shock absorption layer UCF disposedbetween the upper surface of the thin film glass layer TG and the hardcoating layer HC.

The second shock absorption layer UCF is provided on the upper surfaceof the thin film glass layer TG, for example, on the surface facing theuser. The second shock absorption layer UCF may be a layer increasingthe impact resistance of the window FWM2.

The second shock absorption layer LCF may have a thickness within arange of 5 μm to 50 μs. In an embodiment of the present inventiveconcept, the second shock absorption layer UCF may have a thicknesswithin a range of 10 μm. Also, the second shock absorption layer UCF mayhave a Young's modulus within a range of 1 Gpa to 7 Gpa.

According to the window FWM2, the first protection layer LPF1 includes afirst shock absorption layer 1 and an internal adhesive layer IAM. Thestructure of the first protection layer LPF1 shown in FIG. 8B is thesame as that of the first protection layer LPF1 shown in FIG. 8A, andthus a redundant description will be omitted.

As shown in FIG. 9B, in the window FWM2 structure in which the secondprotection layer UPF2 further includes the second shock absorption layerUCF, the curvature radius R2 of the folded out window FWM2 may increase.Under the same conditions, the bendability limit of the window FWM1according to FIGS. 8A and 9A is 2.5 mm, and the bendability limit of thewindow FWM2 according to FIGS. 8B and 9B may be approximately 3.0 mm.For example, the window FWM2 may have a lower bending strength than thewindow FWM1.

However, when the point impact and surface impact tests are performedunder the same conditions, the window FWM1 shown in FIGS. 8A and 9Aabsorbed impacts up to 9 cm height in the point impact and surfaceimpact tests. It is shown that the window FWM2 shown in FIGS. 8B and 9Babsorbs impacts up to 10 cm and 11 cm height in the point impact andsurface impact tests, respectively. For example, the window FWM2including the first shock absorption layer UCF may have a higher impactresistance than the window FWM1.

Referring to FIG. 8C, in the window FWM3, according to an embodiment ofthe present inventive concept, since the second protection layer UPF1has the same structure as the second protection layer UPF1 shown in FIG.8A, a redundant description will be omitted.

The window FWM3 includes a third shock absorption layer LCF2. The thirdshock absorption layer LCF2 may be formed on the rear surface of thethin film glass layer TG through a coating method unlike the first shockabsorption layer LCF1 shown in FIGS. 8A and 8B. For example, the thirdshock absorption layer LCF2 may be directly formed on the rear surfaceof a thin film glass layer TG using a dip coating, a slot die coating, aspin coating, and the like.

The third shock absorption layer LCF2 may have a thickness within arange of 5 μm to 70 μm. In an embodiment of the present inventiveconcept, the third shock absorption layer LCF2 may have a thicknesswithin a range of 50 μm. Also, the third shock absorption layer LCF2 mayhave a Young's modulus within a range of 1 Gpa to 7 Gpa.

Referring to FIG. 8D, in the window FWM4 according to an embodiment ofthe present inventive concept, since the second protection layer UPF2has the same structure as the second protection layer UPF2 shown in FIG.3B, a redundant description be omitted.

In addition, in the window FWM4, since the first protection layer LPF2has the same structure as the first protection layer LPF2 shown in FIG.3C, a redundant description will be omitted.

However, the second shock absorption layer UCF of the second protectionlayer UPF2 and the second shock absorption layer UCF of the secondprotection layer UPF2 are both formed on the thin film glass layer TGthrough a coating method.

Therefore, since the windows FWM3 and FWM4 have a shock absorption layerformed by a coating method, neither window includes the internaladhesive layer IAM (see FIGS. 8A and 8B) as compared with the windowsFWM1 and FWM2 of FIGS. 8A and 8B. Therefore, the total thickness withina range of the windows FWM3 and FWM4 decreases by the thickness within arange of the internal adhesive layer IAM, as compared with the windowsFWM1 and FWM2 of FIGS. 8A and 8B, respectively.

Therefore, when other conditions are the same, the bendability limit ofthe windows FWM3 and FWM4 may be reduced in comparison with the windowsFWM1 and FWM2 of FIGS. 98A and 8B, respectively. For example, thebendability limit of the window FWM3 may be 2.0 mm and the bendabilitylimit of the window FWM4 may be 2.5 mm.

Also, when the internal adhesive layer IAM is removed, even if thefolding operation is repeated for a long time, there is no problem suchas peeling of the internal adhesive layer in the folding area. Forexample, the phenomena such as delamination in the folding area, liftingphenomenon, and the like may be reduced.

FIGS. 10A to 10D are process diagrams showing a manufacturing process ofthe window shown in FIG. 8A.

Referring to FIG. 10A, a window base material MTG may be prepared. Thewindow base material MTG may contain glass. The glass material mayinclude a silicate, and may further include various materials toincrease durability, surface smoothness, and transparency. In anembodiment of the present inventive concept, the window base materialMTG may further include an alkali metal, an alkaline earth metal, anoxide thereof, or the like.

Referring to FIG. 10B, a hard coating material MHC may be formed on oneside of the window base material MTG. The hard coating material MHC mayinclude a urethane resin, an epoxy resin, an acrylic resin, and/or anacrylate resin. As one example of the present inventive concept, thehard coating, material MHC may include an acrylate resin.

The hard coating material MHC may be formed on one side of the windowbase material MTG through a coating method. For example, a hard coatingmaterial MHC may be formed on one side of the window base material MTGusing a method such as slot die coating, spin coating, and the like.

Referring to FIG. 10C, the window base material MTG coated with the hardbase material MHC may be cut along a cutting line CL. The cutting lineCL may be provided in the effective area unit defined in the window basematerial MTG. Accordingly, when the window base material MTG is cut, apreliminary window of a size corresponding to the window FWM1 of FIG. 8Amay be formed. Thus, the preliminary window may include a thin filmglass layer TG and a hard coating layer HC.

Referring to FIG. 10D, the first protection layer LPF1 may be formed onthe rear surface of the thin film glass layer TG. The first protectionlayer LPF1 includes the first shock absorption layer LCF1 and theinternal adhesive layer IAM. The bezel layer BZL may be formed on oneside of the first shock absorption layer LCF1 by an inkjet printingmethod, an imprint method, a silk screen printing method, a laminationmethod, or the like. As an example of the present inventive concept, thebezel layer BZL may be formed on the rear surface of the first shockabsorption layer LCF1.

The internal adhesive layer IAM is disposed between the thin film glasslayer TG and the first shock absorption layer LCF1 to bond the shockabsorption layer LCF1 and the thin film glass layer TG. The order ofadhesion of the internal adhesive layer IAM, the first shock absorptionlayer LCF1, and the thin film glass layer TG is not particularlylimited. After attaching, the internal adhesive layer IAM to the thinfilm glass layer TG, the first shock absorption layer LCF1 may beattached to the internal adhesive layer IAM. In one embodiment of thepresent inventive concept, after attaching the internal adhesive layerLAM to the first shock absorption layer LCF1, the thin film glass layerTG may be attached.

Meanwhile, the first shock absorption layer LCF1 and the thin film glasslayer TG may be attached simultaneously to the internal adhesive layerIAM

Thereafter, a fingerprint prevention layer AF is formed on the hardcoating layer HC to complete the window FWM1 of FIG. 8A. The fingerprintprevention layer AF may be formed by depositing, or spraying afingerprint-resistant material onto the upper surface of the hardcoating layer HC.

FIGS. 11A to 11E are process diagrams showing a manufacturing process ofthe window shown in FIG. 8B.

Referring to FIG. 11A, a window base material MTG may be prepared. Thewindow base material MTG may contain glass.

Referring to FIG. 10B, a hard coating material MHC may be formed on oneside of the window base material MTG. The impact absorbing material MCFmay be formed on one side of the window base material MTG by a coatingmethod. For example, the impact absorbing material MCF may be formed onone side of a window base material MTC using a slot die coating, a spincoating, or the like.

The impact absorbing material MCF may include a urethane resin, an epoxyresin, a polyimide resin, a polyamide resin, and/or an acrylate resin,which may be formed on the window base material MTG through a coatingmethod. As one example of the present inventive concept, the impactabsorbing material MCF may include polyimide PI and/or polyamide PAI.

As an example, when the impact absorbing material MCF is attached to thethin film glass layer TG through the adhesive layer without a coatingmethod, the impact absorbing material MCF may include a polyimide resin,a polyamide resin, a polyester resin, a polyether resin, an acrylateresin, an acrylonitrile-butadiene-styrene (ABS) resin, and/or rubber(e.g. natural or synthetic).

Referring to FIG. 11C, a hard coating material MHC may be formed on theimpact absorbing material MCF. The hard coating material MHC may be madeof an acrylic resin. The hard coating materials MHC may be formed on theimpact absorbing material MCF through a coating process.

Referring to FIG. 11D, the window base material MTG coated with theimpact absorbing material MCF, and the hard coating material MHC may becut along a cutting line CL. The cutting line CL may be provided in theeffective area unit defined in the window base material MTG.Accordingly, when the window base material MTG is cut, a preliminarywindow of a size corresponding to the window FWM2 of FIG. 8B may beformed. Thus, the preliminary window may include a thin film glass layerTG, a shock absorption layer UCF, and a hard coating layer HC.

Referring to FIG. 11E, the first protection layer LPF1 and the bezellayer BZL may be formed on the rear surface of the thin film glass layerTG. The process of forming the first protection layer LDF1 and the bezellayer BZL is similar to that of FIG. 10D, so a detailed descriptionthereof will be omitted.

Thereafter, a fingerprint prevention layer AF is formed on the hardcoating layer HC to complete the window FWM2 of FIG. 8B.

FIG. 12 is an exploded perspective view of a display module according toan embodiment of the present inventive concept. FIG. 13 is an equivalentcircuit diagram of a pixel included in a display panel according to anembodiment of the present inventive concept. FIG. 14 is across-sectional view showing a part of the area of a display moduleaccording to an embodiment of the present inventive concept.

Referring to FIGS. 12 to 14 , a display module DM according to anembodiment of the present inventive concept includes an input detectionunit ISU and a display panel DP.

The input detection unit ISU may be disposed on the display panel DP.The input detection unit ISU detects the external input and obtains theposition and intensity information of the external input. External inputmay be provided by various sources. For example, the external input maybe applied by a part of the user's body (e.g. a finger), light, heat, orpressure. In addition, the input detection unit ISU may detect inputsthat contact and also are close to or adjacent to the input detectionunit ISU.

The input detection unit ISU may include a sensing area SA and anon-sensing area NSA. The sensing area SA may at least partially overlapthe display area DA. The non-sensing area NSA is adjacent to the sensingarea SA. The non-sensing area NSA may surround the edge of the sensingarea SA on at least one side thereof. However, this is illustrativelyshown, and the non-sensing area NSA may be adjacent to only a portion ofthe edges of the sensing area SA, and is not limited to any oneembodiment.

The sensing electrode SS is disposed in the sensing area SA. The sensingelectrode SS may include a first sensing electrode SE1 and a seconddetection electrode SE2 that receive different electrical signals. Thesensing electrode SS may obtain information on an external input TC(shown FIG. 4 ) through a change in capacitance between the firstsensing electrode SE1 and the second sensing electrode SF2.

The first sensing electrodes SE1 may be provided in plural and arrangedso as to be spaced apart from each other along the second direction DR2.The plurality of first sensing electrodes SE1 may be electricallyconnected to each other. The second sensing electrodes SE2 may beprovided in plural and arranged so as to be spaced apart from each otheralong the second direction DR2. The plurality of second sensingelectrodes E2 may be electrically connected to each other.

The touch sensor TS is disposed in a non-sensing area NSA, and mayfurther include detection signal lines for transmitting an electricalsignal provided from the outside to the first sensing electrode SE1, orproviding a signal from the second sensing electrode SE2 to the outside.

The input detection unit ISIS may be directly disposed on the displaypanel DP. For example, the sensing electrode SS or detection signallines may be formed directly on the display panel DP. Alternatively, thetouch sensor TS may be formed separately from the display panel DP, andthen attached on the display panel DP through an adhesive member or thelike. Alternatively, the touch sensor TS may be disposed on the rearsurface of the display panel DP, or disposed within the display panelDP. The touch sensor TS, according to an embodiment of the presentinventive concept, may be provided in various forms and is not limitedto any one embodiment.

Referring, to FIGS. 12 and 13 , a plurality of pixels PX are provided inthe display area DA of the display panel DP. The pixels PX implement animage IM (shown in FIG. 1 ) by displaying light according to anelectrical signal.

As an example of the present inventive concept, each of the pixels PXmay include a first thin film transistor T1, a second thin filmtransistor T2, a capacitor CP, and a light emitting element EMD. Thefirst thin film transistor T1, the second thin film transistor T2, thecapacitor CP, and the light emitting element EMD are electricallyconnected to each other.

The first thin film transistor T1 may be a switching element forcontrolling turn-on and turn-off of the each pixel PX. The first thinfilm transistor T1 is connected to the gate line GL and the data lineDL. The first thin film transistor T1 is turned on by the gate signalprovided through the gate line GL and provides a data signal providedthrough the data line DL to the capacitor CP.

The capacitor CP charges the voltage corresponding to the potentialdifference between the first power signal provided from the power linePL and the signal provided from the thin film transistor T1. The secondthin film transistor T2 provides the light emitting element EMD with afirst power signal provided from the power line PL in correspondence tothe voltage charged in the capacitor CP.

The light emitting element EMD may generate light or control the amountof light according to art electrical signal. For example, the lightemitting element EMD may include an organic light emitting element, aquantum dot light emitting element, an electrophoretic element, or anelectrowetting element.

A light emitting element EMD is connected to a power terminal VSS and isprovided with a power signal that is different from the power signalprovided by the power line PL. In the light emitting element EMD, adriving current corresponding to the difference between the electricsignal provided from the second thin film transistor T2 and the secondpower signal ELVSS flows, and the light emitting element EMD maygenerate light corresponding to the driving current.

The pixel PX may include electronic components having variousconfigurations and arrangements, and is not limited to any oneembodiment.

Referring to FIGS. 13 and 14 , the display panel DP may include a baselayer BL, a pixel defining layer PDL, a light emitting element EMD, anda sealing layer EC. The display panel DP may include a plurality oflight emitting areas PXA and a plurality of non-light emitting areasNPXA arranged in a display area DA. FIG. 14 shows an area where two ofthe light emitting areas PXA are arranged.

The base layer BL may include a plurality of insulating layers and aplurality of conductive layers. The plurality of conductive layers andthe plurality of insulating layers may together form a thin filmtransistor and a capacitor connected to the light entitling element EMD.

The pixel defining layer PDL is disposed on the base layer BL. In thepixel defining layer PDL, predetermined opening parts are defined. Theopening parts may define light emitting areas PXA, respectively.

The light emitting element EMD is disposed on the base layer BL. Thelight emitting element EMD may be disposed at a position correspondingto each of the opening parts. The light emitting element EMD may producean image by generating light according to an electrical signaltransmitted through the thin film transistors T1 and T2 and thecapacitor CP constituting the base layer BL.

In this embodiment, the light emitting element EMD may be an organiclight emitting diode (OLED) element. The light emitting element EMDincludes a first electrode EL1, a light emitting layer EML, and a secondelectrode EL2. The light emitting element EMD may generate light byactivating the light emitting layer EML according to the potentialdifference between the first electrode EL1 and the second electrode EL2.Accordingly, the light emitting areas PXA may correspond to the areaswhere the light emitting layers EML are disposed.

The light emitting areas PXA may have different sizes. For example, eachof the light emitting areas PXA may have a different size depending onthe colors of the emitting light. By providing a light emitting area ofan appropriate size for each of the different colors, it is possible tohave a uniform light efficiency for various colors.

The sealing layer EC covers the light emitting element EMD. The sealinglayer EC may include at least one inorganic film and/or organic film.The sealing layer EC prevents moisture penetration from the outside tothe light emitting element EMD and protects the light emitting elementEMD. In addition, a sealing layer EC may be disposed between the lightemitting element EMD and the input detection unit ISU to electricallyisolate the light emitting element EMD from the input detection unitISU. However, this is illustratively shown, and the sealing layer EC maybe provided as a glass substrate or a plastic substrate. An inert gasmay be filled between the sealing layer EC and the light emittingelement EMD. The display panel DP, according to an embodiment of thepresent inventive concept, may have various structures and is notlimited to any one embodiment.

The input detection unit ISU may be disposed directly on the sealinglayer EC. For example, the input detection unit ISU may be formed bydepositing or patterning on the upper surface of the sealing layer EC.However, this is illustrated by way of example, and the display moduleDM may further include members such as color filters or buffer layersinterposed between the input detection unit ISU and the sealing layerEC.

As shown in FIGS. 12 and 14 , the input detection unit ISU may include aplurality of conductive layers and a plurality of insulating layersstacked on a cross-section. In this embodiment, the input detection unitISU includes a first conductive layer 10, a second conductive layer 20,a first insulating layer 30, and a second insulating layer 40, whichdisposed on different layers.

The first conductive layer 10 is disposed on the display panel DP. Thesecond conductive layer 20 is disposed on the first conductive layer 10.The first sensing electrode SE1 and the second sensing electrode SE2 maybe included in either the first conductive layer 10 or the secondconductive layer 20. The first sensing electrode SE1 may be connected tothe sensing signal lines to receive a touch detection signal. The secondsensing electrode SE2 may be connected to the lead-out lines to outputthe detected signal.

Each of the first conductive layer 10 and the second conductive layer 20includes a plurality of conductive patterns. The conductive patternsinclude the above-described first sensing electrode SE1 and secondsensing electrode SE2.

The conductive patterns constituting each of the first conductive layer10 and the second conductive layer 20 may be arranged so as not tooverlap the light emitting areas PXA on a plane. Accordingly, althoughthe first conductive layer 10 and the second conductive layer 20,according to an embodiment of the present inventive concept, may beformed of an opaque material or may have a large area, this might notadversely affect the image IM displayed on the light emitting areas PXA.However, this is illustratively shown. Each of the first conductivelayer 10 and the second conductive layer 20 may include a conductivepattern disposed to overlap at least a part of the light emitting areasPXA, but are not limited to any one embodiment.

The first insulating layer 30 is disposed between the first conductivelayer 10 and the second conductive layer 20, The first insulating layer30 isolates and separates the first conductive layer 10 and the secondconductive layer 20 from each other on a cross-section. Some of thefirst conductive layer 10 and the second conductive layer 20 may beelectrically connected through a contact hole CH that penetrates thefirst insulating layer 30.

The second insulating layer 40 is disposed on the first insulating layer30. The second insulating layer 40 may cover the second conductive layer20. The second insulating layer 40 protects the second conductive layer20 from the external environment.

The first insulating layer 30 and the second insulating layer 40 eachhave an electrically insulating property and may be opticallytransparent. Accordingly, even though the light emitting area PXA iscovered by the first insulating layer 30 and the second insulating layer40, light generated from the light emitting area PXA may be easily seenat the upper part of the input detection unit ISU.

The first insulating layer 30 and the second insulating layer 40 mayinclude at least one inorganic film and/or organic film. For example, ifthe first insulating layer 30 and the second insulating layer 40 mainlyinclude an organic film, the softness of the input detection unit ISUmay be increased. Alternatively, for example, if the first insulatinglayer 30 and the second insulating layer 40 mainly include an inorganicfilm, a thin input detection unit ISU may be provided and an inputdetection unit ISU with increased impact resistance may be provided. Thefirst insulating layer 30 and the second insulating layer 40, accordingto an embodiment of the present inventive concept, may include variousmaterials and are not limited to any one embodiment.

According to an embodiment of the present inventive concept, in a windowcontaining a thin film glass layer in the base layer, by providing ahard coating layer on the upper surface of the thin film glass layer, itis possible to prevent a phenomenon that fine cracks are generated inthe thin film glass layer due to point impacts or surface impactsprovided from the outside, and the shape deformation such as stampingand pressing occurs.

As a result, the impact resistance of the window and the display deviceemploying the window may be increased.

Although the exemplary embodiments of the present inventive concept havebeen described, it is understood that the present inventive conceptshould not be limited to these exemplary embodiments but various changesand modifications may be made by one ordinary skilled in the art withinthe spirit and scope of the present disclosure.

What is claimed is:
 1. A display device, comprising: a flexible displaypanel configured to display an image from a display surface thereof; anda window disposed on the display surface of the flexible display panel,wherein the window comprises: a thin film glass layer; and a protectionlayer disposed on the thin film glass layer, wherein the protectionlayer includes a hard coating layer and a shock absorption aver disposedbetween the hard coating layer and the thin film glass layer, andwherein the hard coating layer directly contacts the shock absorptionlaver.
 2. The display device of claim 1, wherein the window furthercomprises an oleophobic coating disposed on the hard coating layer. 3.The display device of claim 1, wherein the thin film glass layer has athickness within a range of 30 μm to 70 μm.
 4. The display device ofclaim 1, wherein the flexible display panel comprises an organic lightemitting diode (OLED) display panel including an organic light emittingelement.
 5. A display device, comprising: a display panel configured todisplay an image from a display surface thereof, the display panelincluding a folding area, in which the display panel is folded around afolding axis, and a plurality of non-folding areas adjacent to oppositesides of the folding area; and a window disposed on the display surfaceof the display panel, wherein the window comprises: a thin film glasslayer, and a protection layer disposed on the thin film glass layer,wherein the protection layer comprises a hard coating layer and a shockabsorption layer disposed between the hard coating layer and the thinfilm glass layer, and wherein the hard coating layer directly, contactsthe shock absorption laver.
 6. The display device of claim 5, whereinthe display panel is configured to be folded out, such that the displaysurface is exposed to the outside, or folded in such that the displaysurface is covered.
 7. The display device of claim 5, wherein the hardcoating layer has a thickness within a range of 3 μm to 30 μm.
 8. Thedisplay device of claim 5, wherein the hard coating layer comprises aurethane resin, an epoxy resin, an acrylic resin, and/or an acrylateresin.
 9. The display device of claim 5, wherein the hard coating layerhas an indentation hardness within a range of 15 HV to 40 HV.
 10. Thedisplay device of claim 5, wherein the window further comprises anoleophobic coating disposed on the hard coating layer.
 11. The displaydevice of claim 5, wherein the shock absorption layer has a thicknesswithin a range of 5 μm to 50 μm.
 12. The display device of claim 5,wherein the shock absorption layer comprises a urethane resin, an epoxyresin, a polyimide resin, a polyamide resin, and/or an acrylate resin.13. The display device of claim 5, wherein the display panel comprisesan organic light emitting diode (OLED) display panel including anorganic light emitting element.
 14. A display device, comprising: adisplay panel configured to display an image from a display surfacethereof, the display panel including a folding area, in which thedisplay panel is folded around a folding axis, and a plurality ofnon-folding areas adjacent to opposite sides of the folding area; and awindow disposed on the display surface of the display panel, wherein thewindow comprises: a thin film glass layer; a hard coating layer disposedon a front surface of the thin film glass layer; a shock absorptionlayer disposed between the hard coating layer and the thin film glasslayer; and an adhesive layer disposed between the shock absorption layerand the thin film glass layer.